1. Field of the Invention
This invention relates to magnetic heads and, more particularly, to a write head with a T-shaped write pole.
2. Background of the Invention
A write head is used in a magnetic read/write device to write a magnetic bit onto a recording medium of a magnetic storage device. An example is the read/write head of a computer hard disk, which is positioned closely adjacent to the recording medium and separated from the recording medium by an air bearing. A data bit is written onto an area of the recording medium, typically a track moved past the read/write head, using the writing portion of the read/write head by locally changing the magnetic state of the recording medium. That magnetic state is later sensed by the read sensor to read the data. The write structure and the read structure are usually integrated together in a read/write head.
In one design, the write structure includes a small-scale horseshoe-like electromagnet with the poles oriented perpendicular to the air bearing surface (ABS) of the read write head. Because of the small size, the electromagnet, including the legs of the horseshoe, the pole layers, the inductive coil, and the related structure, are fabricated by microelectronic techniques as multilayered structure. The poles at the ends of the legs and adjacent to the ABS are typically designated as the lower pole (also called first pole, or P1 pole) and upper pole (also called second pole, or P2 pole.) A continuing trend in the industry is to make the tracks in the recording medium ever narrower, so that more information may be stored on the recording medium.
In order to write onto a narrow track on the recording medium, the upper pole is made very narrow and has reached submicron widths in current writing devices. To reach even smaller sized, a wider third pole (P3) layer may be added to support and aid in the fabrication of the upper pole layer. Viewed from the ABS. the third pole and upper (P2) layer together have a T-shape, with the wider third pole layer forming the crosspiece of the T. T-shaped pole piece structures are known in the art and are described, for example, in U.S. Pat. No. 5,283,942.
Although the T-head structure successfully allows the fabrication and use of the narrower P2 pole layer for writing onto ever narrower tracks in the recording medium, the inventors have observed other problems in the work leading to the present invention. Specifically, the T-head structure may perform “corner writing”, an unintended alteration of the recording medium off of the intended track. There is a need for an approach to avoid corner writing, while at the same time realizing the benefits of the T-head write structure. The present invention fulfills this need, and further provides related advantages.